Sandoz Limited v Bristol-Myers Squibb Holdings Ireland Unlimited Company

A patent claim to a single chemical compound requires more than disclosure of the compound’s structure and synthesis. Where patentability depends on an asserted utility, the application, read with the skilled person’s common general knowledge, must make that utility plausible.

The application must give the skilled person a reason to think there is a reasonable prospect that the asserted effect will prove true. A bare assertion, an invitation to conduct simple tests, or favourable post-filing evidence cannot supply the missing technical contribution. These principles apply whether the asserted use forms part of the claim or appears only in the specification.

The proprietor held a patent claiming apixaban, a compound subsequently shown to be a potent factor Xa inhibitor used to treat thromboembolic disorders. Sandoz and Teva challenged the patent and the associated supplementary protection certificate. The Patents Court held the patent invalid because the application did not make apixaban’s useful factor Xa inhibitory activity plausible: [2022] EWHC 822 (Pat).

The proprietor appealed. It relied principally on a passage stating that unidentified compounds had achieved specified assay results and on the unusually large quantity of apixaban produced in Example 18. The central issues were whether plausibility applied to a claim for one chemical compound, what standard governed, and whether the application made the asserted utility plausible.

1. Appeal dismissed. The judge correctly applied the majority approach in Warner-Lambert. A patent claim to a single chemical compound is not exempt from the requirement that the asserted technical effect be plausible. The scope of every patent monopoly, broad or narrow, must be justified by the patentee’s technical contribution to the art.

2. Where a compound’s asserted utility supplies the inventive concept, the application, read with the skilled person’s common general knowledge, must make that utility plausible. Merely identifying a new compound is not an invention. This remains so whether the use is a technical feature of the claim or is asserted only in the specification. If no solution to a technical problem is made plausible, the claimed subject matter lacks an inventive step and the specification discloses no invention sufficiently.

3. The governing standard was that adopted by the Supreme Court majority in Warner-Lambert. The application must give the skilled person a reason to think there is a reasonable prospect that the asserted effect will prove true. The approach in G 2/21, which asks whether the technical effect is encompassed by the technical teaching derivable from the application and common general knowledge, did not justify departing from that binding standard.

4. An application does not make an effect plausible merely by encouraging the skilled person to conduct simple tests, even where the tests are identified, easy to perform and would confirm efficacy. Later data cannot substitute for a sufficient disclosure in the application.

5. Plausibility involved a multifactorial evaluation. The trial judge’s assessment could be displaced only for an error of law or principle. No such error occurred. The application did not connect apixaban to the reported assay results. The quantity synthesised and second recrystallisation did not establish why that quantity was made. Other explanations remained possible. The application therefore supplied no reason to expect apixaban to possess useful factor Xa inhibitory activity. Subsequent proof of efficacy and restriction of the patent claim to apixaban were irrelevant.

1. Court of Appeal (Civil Division): The proprietor’s appeal was dismissed unanimously: [2023] EWCA Civ 472.

2. High Court, Patents Court: Meade J held the patent invalid because the application did not make it plausible that apixaban possessed useful factor Xa inhibitory activity: [2022] EWHC 822 (Pat).